Walsh would have partnered Al Ferof, who was ruled out for the season on Monday, but will now replace the suspended Daryl Jacob aboard Nicholls' stablemate.

The Ditcheat handler has also earmarked several horses who could represent him in the Ladbrokes World Hurdle, a race the injured Big Buck's has won for the last four years.

"Ruby will now ride Kauto Stone in the King George and, looking at the World Hurdle, we have Wonderful Charm, Prospect Wells and perhaps even TidalBay to consider for that race," Nicholls told Betfair.

"Wonderful Charm has had a breathing operation since winning at Chepstow, and I may even consider Tidal Bay for the Cleeve Hurdle after he runs in the Lexus.

"For sure, he (Tidal Bay) has enough talent and versatility to make his presence felt in the World Hurdle, as well as the Gold Cup."